Experiment And Numerical Simulation Research On The Double Pipe Gas Jet Of Underwater Vehicle

The phenomenon of underwater gas jet refers to the phenomenon that the air flows out of the pipe at a certain speed,diffuses into the water environment and forms a complex water gas two-phase mixed flow.Underwater weapons,such as submarine launched vehicle with power and supercavitating vehicle with water ramjet engine as power source,jet high-pressure gas from the tail of the engine into the water to form the tail jet of the underwater vehicle.The problem of jet flow in the tail of underwater vehicle is related to the multiphase flow field in which the subsonic and transonic gas jets are coupled with the water medium with the same velocity.During the acceleration process of supercavitating torpedo,the booster engine and the main engine work at the same time,which also involves the interference and fusion of multi-channel jet flow field.In this paper,a water tunnel experiment is designed to study the transient and steady flow characteristics of the double pipe gas jet at the tail of an underwater vehicle.STARCCM + is used to establish the calculation model of double pipe gas jet at the tail of underwater vehicle,and the transient flow field characteristics of double pipe gas jet at the tail of underwater vehicle under static water environment and incoming flow are systematically studied.Firstly,a simplified model of double pipe gas jet at the tail of underwater vehicle is designed by consulting the literature.Based on the circulating water tunnel equipment of the research group,an experimental test system is built.In the aspect of numerical simulation,the turbulence model and multiphase flow model suitable for this paper are selected,and the numerical calculation method and algorithm verification are completed.Experiments and numerical simulation of double pipe gas jet at the tail of underwater vehicle in still water are carried out.Through experiments,the initial evolution law of jet under different ventilation flow rates is summarized,and the influence of ventilation flow rate on steady-state jet shape and pressure fluctuation of steady-state jet in pipe exit section is studied.Through the numerical simulation,the law of the internal pressure change in the initial evolution process of the jet is obtained.The experiment and numerical simulation of the double pipe gas jet at the tail of the underwater vehicle under the action of incoming flow are carried out,and the initial evolution law of the double pipe gas jet and the variation law of the internal pressure of the jet are obtained.Experiments and simulations are carried out under different inflow velocities and ventilation flow rates,and the effects of the above two factors on the fusion time and the effective length of steady-state jet are summarized.By analyzing the frequency spectrum of jet pressure fluctuation signals under different working conditions,the influence law of flow and gas jet on the pressure oscillation characteristics of the flow field is obtained.